Results: As of Nov 2012, 53 pts had received a median of 22 CRd cycles (range 2–24); 7 pts opted for transplant; 24 continued LEN maintenance for median 8 mo (range 1–10). Median follow-up was 25 mo (range 5–37). With extended tx, the CR rate was 64%; sCR improved from 42% to 53%, ≥nCR from 62% to 72%, and ≥VGPR from 81% to 87% (follow-up 13 vs 25 mo); ≥PR remained at 98%. Immunophenotypic CR (IMWG) was achieved in 22/26 evaluated pts. Of pts in sCR, 25% had high-risk cytogenetics per IMWG. In pts who did not proceed to transplant (n=46), the sCR was 59%, CR 70%, ≥nCR 78%, ≥VGPR 91%, and ≥PR 100%. Over the course of tx, depth of response improved. Median time to ≥VGPR was 4 cycles (range 2–17), ≥nCR 4.5 cycles (range 2–15), and sCR 10 cycles (range 4–30); 2 pts converted to sCR during LEN maintenance. At 2 years, the estimated PFS rate was 94% and OS was 98%; for pts with sCR, rates were 96% and 100%, respectively. Adverse event types, rates, and dose modifications during extended tx were comparable with those previously reported. There was 1 death off study due to disease progression.

Conclusions: Extended follow-up showed that depth of response continued to improve over the course of prolonged CRd tx, resulting in exceptional CR, sCR, and PFS. Extended tx continued to be well tolerated. The results compare favorably with historical studies in both transplant and non-transplant NDMM.